1. Field                The present invention relates to a method, system, and an article of manufacture for switching a mode of operation.        
2. Description of the Related Art
Computer systems frequently have more than one mode of operation. For example, a computer system may have a normal operational mode for normal operations. In addition, a service mode is often provided to facilitate troubleshooting and other operations. Various input devices have been utilized to switch the mode of operation to a service mode. For example, a computer system may have a key-operated switch which has a “normal operation” position and a “service operation” position. An operator may insert the key into the switch and turn the switch to the “service operation” position to switch the mode of operation of the system from the normal operational mode to a service mode.
Other computer systems have a keyboard with various input keys. In one known computer system, depressing a key at an appropriate time during the boot operation may cause the computer system to interrupt the normal boot mode of operation and switch to a different boot mode which leads to a service operational mode sometimes referred to as a “safe mode” to facilitate troubleshooting.
A computer system may have one or more embedded devices, each of which may itself be a specialized computer system that is part of a larger system such as a host computer system. For example, a storage controller may be embedded in a host computer. The embedded storage controller may be housed on a single microprocessor board with the programs stored in ROM or other types of memory. Some embedded systems include an operating system. Other embedded systems may be so specialized that the entire logic can be implemented as a single program.
An embedded system may itself have, like a host system, multiple operational modes including a service mode. For example, the Enterprise Storage System (ESS), an embedded storage controller marketed by IBM Corporation, has a service mode which may be entered during the boot process. This embedded storage controller has an operating system which is loaded as a user process of the operating system of the host computer. Hence, in this example, the embedded storage controller operating system may be loaded as a part of a startup sequence initiated as the operating system of the host computer system is loaded. The embedded storage controller operating system may have its own startup sequence which, absent operator intervention, loads code which permits normal operation.
However, should the operator wish to direct the embedded storage controller to the storage controller service mode instead of the storage controller normal operation mode, the operator can insert a special program stored on a floppy disk into a floppy disk drive mounted on the embedded storage controller chassis and restart the host computer. As the host computer startup sequence initiates the embedded storage controller startup sequence, the embedded storage controller startup sequence detects the special program on the floppy disk and loads the service mode code instead of the normal operation mode code. The operator may then operate the storage controller in the service mode to perform troubleshooting or other operations appropriate for the service mode.
To switch back to the normal operational mode for the embedded storage controller, the floppy disk containing the special program may be removed from the storage controller floppy disk drive and the host computer may be restarted. As the host computer startup sequence initiates the embedded storage controller startup sequence, the embedded storage controller startup sequence does not detect the special program on a floppy disk and loads the normal operation mode code instead of the service mode code.